While corrosion problems have plagued the scrubber industry for years, with the recent addition of scrubbing systems to power plants, a variety of costly materials problems have evolved. Little information is available concerning the actual performance of materials incorporated into the various parts of complex scrubbing systems. In order to maintain or increase system reliability and lower component replacement costs, research programs have been initiated by various utilities and general testing facilities.
Information in the scrubber industry is in a general state of flux and is not readily transferrable from one system to another. Little information is available concerning the actual performance of materials incorporated into the various parts of the complex scrubber systems. Additionally, the atmosphere is generally corrosive, with such elements as chloride attacking scrubber components in a highly localized manner, e.g., in welds or crevices. While testing has been generally conducted to attempt to determine anticipated materials performance, the results in practice have often varied from what was expected. In large measure, this is probably due to multiple and often unknown variables within a scrubber system.
A further problem is involved in testing of materials in view of a peculiarity in many of electric generating plants, generally in that corrosion in the generating system usually takes places by pitting of materials and the corrosion is variable from one position to another in the system. Specific materials also are subjected to corrosion at different rates depending upon location in the system.
Heretofore, different types of testing devices have been used, such as, for example, electric resistance testing devices and test coupons, adapted for positionment in different areas or regions of a generating and scrubbing system. Neither of these devices are entirely suitable for measuring what appears to be the primary problem in scrubbers, i.e., pitting, as opposed to general corrosion. This is due to the fact that with pitting, there may be no loss of specific cross sectional area which could result in changes in evaluation of electrical resistance. In order to obviate this drawback, it appears that the only reliable means to evaluate pitting involves both visual inspection and a laboratory analysis of affected materials.